Plant Profile & Key Characteristics
Overview: Callistemon (Melaleuca viminalis, bottlebrush) is an evergreen shrub to small tree, 0.5-6 m, grown as an ornamental for its showy red or white bottlebrush flower spikes; drought-tolerant and suitable for bonsai.
Quick Specifications
| Specification | Attribute |
|---|---|
| Plant Type / Life Cycle | Perennial (evergreen) |
| Foliage Type | Evergreen |
| Mature Size | 0.5-6 m (2-18 ft) |
| Growth Rate | Fast to moderate |
| Toxicity | Non-toxic |
| Hardiness | USDA 7+ |
Growth Form & Structure
- Height & Spread: 0.5-6 m (2-18 ft); container-friendly and used for bonsai.
- Growth Habit & Form: Woody evergreen shrub to small tree, often with arching or weeping branches.
- Lifespan & Maturity: Fast-to-moderate growth; long-lived.
Anatomy & Physical Features
- Leaves & Foliage: Narrow, lance-shaped (lanceolate) green leaves.
- Flower Characteristics: Small needle-like flowers massed into red or white bottlebrush spikes (see Bloom guide).
Primary Uses & Landscape Value
- Functional & Ornamental Roles: Ornamental flowering shrub or hedge, bonsai subject, and drought-tolerant, bird- and pollinator-attracting planting.
Care Guide: Planting, Soil & Watering
Overview: Callistemon (bottlebrush) is a fast- to medium-growing evergreen shrub-to-tree (zone 7+) that grows best in full sun and is drought tolerant once established. It wants well-draining soil and only low to moderate watering.
Quick Care Requirements
| Requirement | Ideal Condition |
|---|---|
| Planting Season | Autumn, winter or spring |
| Growth Rate | Fast to Moderate |
| Soil Type | Well-draining |
| Water Need | Low to Moderate |
Planting & Establishment
- Best Planting Season: Plant in autumn, winter or spring.
- How to Plant:
- Hole Preparation: Dig a hole wider than the root ball in a sunny, free-draining position.
- Soil Amendments: Loosen the backfill and improve drainage; heavy enrichment is not needed.
- Planting Depth: Set the root ball at its original depth with the collar at soil level, firm gently and mulch.
- Growth Speed & Expectations: Fast to medium — reaches about 0.5–6 m (2–18 ft); can be kept smaller by pruning or grown as bonsai.
Soil, Watering & Drainage Care
- Soil Mix & Drainage Needs: Well-draining soil to prevent root rot; it also grows in a container with a free-draining mix and drainage holes.
- Watering Schedule & Technique:
- Young / Newly Planted: Water regularly at first to help roots establish.
- Established: Water lightly to moderately, letting the top of the soil dry between waterings; it tolerates dry spells well.
- Seasonal Adjustments: A little more in summer heat and much less in cool, wet weather.
Climate, Light & Hardiness
Callistemon (bottlebrush) is a broadly adaptable evergreen shrub-to-tree grown across tropical, subtropical, temperate, Mediterranean and desert climates in full sun. Its USDA zone 7+ rating gives it real winter cold tolerance, though hardiness varies noticeably among the many bottlebrush species and cultivars.
Quick Climate Specifications
| Climate Zones | Tropical, Subtropical, Temperate, Mediterranean, Desert |
|---|---|
| USDA Hardiness Zones | 7+ |
| Frost Tolerance | Moderate |
| Light Conditions | Full Sun |
Sunlight & Light Exposure
Optimal Light Setup
Needs full sun for dense growth and the best bottlebrush flowering.
Direct Sun Requirement
Yes - this genus flowers poorly and grows leggy without strong direct sun.
Shade & Heat Management
Handles hot, sunny sites across its wide climate range without needing shade relief.
Best Exposure / Orientation
An open, unshaded position, whether as a garden shrub, small tree, or bonsai specimen.
Temperature Extremes & Hardiness
USDA Hardiness & Regional Limits
Hardy outdoors from USDA zone 7 upward, one of the wider cold-tolerance ratings among bottlebrush species/cultivars on this site - cold tolerance varies by species, cultivar, plant age, and site exposure, so treat zone 7 as an approximate guide rather than a guarantee for every form sold as "Callistemon."
Cold Damage & Winter Protection
Younger plants are generally more cold-sensitive than established specimens; in the coldest parts of its range, siting against a warm wall or providing winter mulch around the root zone reduces risk.
Frost Sensitivity
Moderate frost tolerance once established, consistent with its zone-7 rating.
Extreme Heat Tolerance
Very good - thrives in the heat of desert, subtropical, and Mediterranean summers as a drought-tolerant plant.
Wind, Humidity & Microclimate
Dry-Air Tolerance
Copes well with the low humidity typical of Mediterranean and desert climates, in keeping with its drought tolerance.
Rainfall & Seasonal Moisture
Adaptable across climates with very different rainfall patterns, from humid tropics to dry desert, provided the soil is well-drained.
Microclimate Recommendations
An open, sunny site with good drainage suits it across nearly all of its listed climate zones.
Growing in Pots, Balconies & Indoors
Callistemon (Melaleuca viminalis) is a large shrub or small tree of 0.5-6 m (2-18 ft) prized for its brush-like flowers, and the grower confirms it grows in containers though not as a houseplant. Give it full sun; in a pot it makes a fine patio or balcony feature.
Quick Details
- Container Size: 30-50 L (8-13 gal) for a shrub, sized to the plant
- Indoor Suitability: Not a houseplant; needs full sun outdoors
- Best Spot: Full sun
- Soil & Drainage: Free-draining, slightly acidic loam-based mix
- Watering in Pots: Moderate – keep evenly moist in growth, drier once established; let the surface dry between waterings
Indoors & On the Windowsill
- Not a houseplant: The grower does not recommend it indoors – it is a full-sun shrub or tree that needs open light and airflow it cannot get in a room.
- On the windowsill: Even a bright sill rarely gives enough light for good flowering; it belongs on a sunny balcony, patio or in the garden.
- Overwintering: Fairly tender – in cold-winter regions move the pot to a bright, frost-free spot for the cold season, keeping it only just moist.
On a Balcony or Patio
- Light & wind: Give it the brightest spot the balcony offers; shelter exposed plants from strong wind and stake any tall or top-heavy growth. Walls and paving reflect heat, so pots dry quickly – check moisture often in warm weather.
- Practicalities: A filled pot is heavy once watered, so make sure the balcony can take the weight and stand it where drainage runoff will not be a nuisance.
Choosing the Pot, Soil & Long-Term Care
- Pot & drainage: 30-50 L (8-13 gal) for a shrub, sized to the plant with strong drainage holes; skip a standing water saucer so the roots never sit wet. Terracotta breathes and dries fast, while glazed or plastic pots hold moisture longer.
- Potting mix: A free-draining, loam-based mix on the slightly acidic side; these plants dislike very limey soils.
- Watering: Low to moderate once established – keep young plants evenly moist and let the surface dry between waterings; ensure sharp drainage.
- Feeding: Potted plants exhaust their soil faster because nutrients leach out with every watering – feed lightly but regularly through the growing season.
- Repotting: Refresh the mix or pot up about every couple of years, teasing out and lightly trimming the roots of established plants.
Fertilizing & Feeding
A light feeder once established: this drought-tolerant native needs only modest balanced feeding to fuel its bottlebrush flowers, with feeding eased off through its dry rest period.
Quick Fertilizing Specs
| Feeding Level | Light feeder once established |
|---|---|
| Main Nutrient Priority | Balanced feeding with adequate nitrogen; avoid pushing bloom with extra phosphorus |
| Best Feeding Period | As new growth begins ahead of the bloom period, tapering off once flowering finishes |
| Organic Options | Compost or well-rotted organic matter worked into the root zone |
| Reduce/Stop Feeding | Ease off feeding through the hottest, driest part of the year and while the plant rests |
| Micronutrients | Usually met by a complete fertilizer in well-drained soil; correct only a diagnosed deficiency |
| Soil pH | Tolerates a wide range but performs best in slightly acidic to near-neutral, well-drained soil |
Feeding by Growth Stage
Active growth ahead of bloom
Support fresh lanceolate foliage and flower bud formation as the plant heads toward its bottlebrush bloom.
| Nutrient direction | A balanced, nitrogen-forward complete fertilizer supports healthy foliage and sets up strong flowering. |
|---|---|
| Timing | As new growth resumes heading into the bloom season. |
| Frequency | A light feeding at the start of active growth is usually enough for an established plant. |
| Fertilizer types | A balanced complete fertilizer, Compost or well-rotted organic matter worked into the root zone |
| Precautions | Keep feeding light on this drought-tolerant native; overly rich soil can encourage weak, leggy growth and feed the invasive spread this species is known for. |
Bottlebrush bloom
Sustain the plant through its red or white bottlebrush-shaped flower display.
| Nutrient direction | Continue a balanced complete fertilizer; adequate nitrogen and overall balance drive flowering better than extra phosphorus. |
|---|---|
| Timing | During the winter into spring bloom period. |
| Frequency | Feeding needs stay light through bloom; an established plant rarely needs more than what was applied earlier. |
| Fertilizer types | A balanced complete fertilizer |
| Precautions | Skip high-phosphorus ‘bloom booster’ products; they are not needed to produce a full flush of bottlebrush flowers. |
Rest through the dry season
Let the plant coast through the hottest, driest part of the year without pushing soft new growth.
| Nutrient direction | None – withhold fertilizer while the plant rests after flowering. |
|---|---|
| Timing | After flowering finishes, through the hottest and driest part of the year. |
| Frequency | No feeding at this stage; resume only when active growth begins again. |
| Fertilizer types | No feeding at this stage; hold off fertilizing until new growth resumes. |
| Precautions | Withhold fertilizer now; feeding this resting, drought-tolerant native wastes nutrients and can encourage salt buildup in well-drained soil. |
Nutrient Deficiency Signs & Corrections
Older leaves fade to pale green or yellow and new growth is sparse or slow.
| Possible causes | low available soil nitrogen, nitrogen leaching after heavy rain or watering, poor, sandy well-drained soil with little organic matter |
|---|---|
| Appears first on | older, lower leaves |
| What to check | recent feeding history, soil organic matter levels, drainage and recent rainfall |
| Possible correction | Apply a balanced complete fertilizer with adequate nitrogen and work in organic matter. |
New leaves turn yellow between green veins while the veins themselves stay green.
| Possible causes | high soil pH limiting iron availability, waterlogged or poorly aerated roots, naturally low soil iron |
|---|---|
| Appears first on | newest growth at branch tips |
| What to check | soil pH, drainage around the root zone, whether nearby plants show the same pattern |
| Possible correction | Correct soil pH toward neutral where possible and apply a chelated iron product per its label. |
Leaf tips and margins brown or scorch even though the plant is watered normally.
| Possible causes | fertilizer salt buildup in well-drained soil that is rarely leached, under-watering that concentrates salts, over-fertilizing a naturally light-feeding native |
|---|---|
| Appears first on | leaf tips and margins |
| What to check | recent fertilizer amounts and frequency, watering consistency, soil drainage |
| Possible correction | Ease off feeding, water deeply to flush accumulated salts, then return to a lighter feeding routine. |
Pruning, Training & Seasonal Maintenance
Callistemon (bottlebrush) is a fast-to-medium-growing evergreen shrub, sometimes trained as a small tree or bonsai, that takes well to light-to-moderate shaping but does not reliably reshoot from bare, leafless old wood – cuts should stay within actively leafy growth. Its cylindrical, brush-like flower spikes form mainly through winter–spring, so the most effective and lowest-risk time to shape it is right after that main flush fades, when removing spent spikes both tidies the plant and pushes out the side shoots that will carry next season’s flowers.
Quick Pruning & Maintenance Specs
| Pruning Tolerance | Moderate (shaping and deadheading tolerated; hard cuts into bare wood are not) |
| Primary Pruning Window | Immediately after the winter–spring bloom flush fades |
| Secondary Maintenance Window | Light structural tidy in autumn, kept clear of swelling flower buds |
| Typical Frequency | Once after each main bloom flush, plus occasional light tidy |
| Main Objective | Shape and deadhead without sacrificing next season’s flower spikes |
| Young Plant Priority | Establish an even branch structure; light tip pruning to encourage bushiness |
| Mature Plant Priority | Post-bloom deadheading and shape maintenance; watch for legginess |
| Best Tool Type | Bypass secateurs for spikes and small stems; loppers for older shrub wood |
| Avoid Heavy Pruning During | The active winter–spring bloom period, and any cutting into fully bare wood |
Pruning by Plant Age & Size
Newly Established
Let a young plant settle in before shaping; remove only damaged growth for the first season.
Young / Formative
Light tip pruning encourages branching and a fuller shrub; if being trained as a small standard tree, select and stake a leader and remove competing low shoots, otherwise no formal leader/vase system is needed – a naturally rounded shrub form is normal.
Mature / Established
Post-bloom deadheading and light shape correction; occasional renewal removal of the oldest, weakest stems from the base on a multi-stem shrub to keep vigor.
Seasonal Pruning Schedule
Post-Flowering
Objective: deadhead and shape. Remove: spent flower spikes, cutting just behind them into leafy growth. Do not remove: healthy leafy stem beyond what’s needed for shape. Expected response: new shoots typically emerge from just below the spent spike, setting up the next flowering flush. Flowering impact: this is the safest time to cut – it does not remove developing buds.
Ongoing Sanitary
Remove dead, damaged, or aphid-affected growth as noticed; a light autumn tidy is fine provided it avoids stems already carrying swelling flower buds for the coming winter–spring display.
Flowering & Fruiting Wood
Flower spikes form at the tips of stems that hardened off during the previous growth flush. New vegetative growth typically continues from just behind the spent spike – a distinctive habit in this family – so deadheading close behind the spike costs little stem length while stimulating the branching that carries next season’s spikes. Hard pruning into fully bare, leafless wood removes future flowering positions and often fails to reshoot at all.
Structural Pruning & Training
Remove crossing or rubbing branches; control height and spread by cutting back to an outward-facing leafy node, never into bare wood; light canopy thinning can improve airflow in humid conditions but is not routinely required.
Special Growth to Remove
Basal shoots: if trained as a small single/multi-trunk tree, remove basal suckers to preserve that form; if grown as an informal shrub, they can be left for fullness. Spent flower spikes as described above.
Container & Small-Space Pruning
This species stays compact enough for pots and is a favored bonsai subject. In containers, prune a little more frequently and lightly than in-ground specimens to match the smaller root volume, and use post-bloom deadheading to keep a tight, well-branched shape rather than letting it stretch.
Tools
Bypass secateurs for spike deadheading and small-stem shaping; loppers for thicker stems on a mature multi-stem shrub.
Tool Hygiene & Disease Risk
Routine – clean, sharp tools are sufficient; aphids are the main pest of note but are not tool-transmitted.
Cut Placement & Technique
Cut to an outward-facing leafy node or junction; use thinning cuts for structural work rather than indiscriminate heading, and never cut into wood with no live foliage below the cut.
Heavy Pruning & Rejuvenation
Tolerance for hard rejuvenation is limited, since regrowth from bare old wood is unreliable in this family. If renewal is needed, stage it – remove no more than about a third of the framework in a season, always cutting back to a point with live leaves or visible dormant buds.
Post-Pruning Care
Water normally; watch new flushes of soft growth after pruning for aphids, its noted pest.
Common Pruning Mistakes
Cutting into leafless old wood expecting it to reshoot; pruning right before or during the bloom flush and losing the display; shearing into a formal hedge box, which this species does not reshoot into cleanly and which ruins the natural spike display.
When NOT to Prune
Avoid pruning during the active winter–spring bloom, and avoid cutting into completely bare wood at any time.
Recommended Tools (by task)
- Deadheading spikes / young shaping: bypass_secateurs – clean cuts on spikes and pencil-thick stems without crushing.
- Older multi-stem wood on a mature shrub: loppers – handles the thicker basal renewal cuts secateurs can’t.
- Training as a single-trunk standard/bonsai form: soft_ties_stakes – supports a selected leader while young.
Pruning Troubleshooting
| Problem | Possible Cause | What to Check | Corrective Action |
| Stem dieback after a hard cut | Cut made into leafless/bare old wood | Whether the cut point had any live leaves or buds nearby | Always cut back to a point with live growth; stage heavier renewal over seasons |
| Reduced flowering the following season | Pruned right before or during bloom, removing developing buds | Timing of the last prune relative to the bloom season | Shift primary pruning to right after the bloom flush fades |
| Sparse, leggy growth | No post-bloom shaping performed | Time since the last deadheading pass | Begin routine post-bloom tip pruning and deadheading |
Propagation Guide
Callistemon is most simply raised from seed, which the species produces abundantly in woody capsules that persist along the stems, but semi-hardwood cuttings are the method used to keep a particular flower color or bonsai-trained form true to the parent plant. Difficulty is easy from seed and moderate from cuttings.
Quick Propagation Specs
| Best Propagation Method | Seed (species); semi-hardwood cuttings for named color forms or bonsai stock |
| Alternative Methods | Semi-hardwood cuttings |
| Propagation Difficulty | Easy (seed) to Moderate (cuttings) |
| Seed True-to-Type | Usually true-to-type for the species; cultivar-dependent for named color selections |
| Vegetative True-to-Type | Yes |
| Best Propagation Season | Sow seed in spring; take cuttings in summer |
| Cutting Rooting Time | Several weeks to a couple of months |
| Seed Sowing Depth | Surface-sow or barely cover – seed is very fine |
Growing from Seed
Seed Handling & Viability
Seed is held in small woody capsules that persist along older stems; capsules can be collected and dried to release the fine seed inside.
Sowing Season
Spring.
Sowing Depth & Orientation
Seed is tiny; surface-sow or cover only very lightly, and keep the mix from drying out.
Germination Conditions
Warm conditions favor germination; expect results within a few weeks, though timing can vary.
Stem Cuttings
Cutting Type
Semi-hardwood tip cuttings, useful for preserving a specific flower color or a trained bonsai form.
Best Timing
Summer.
Rooting Hormone
Often beneficial for improving strike rate on semi-hardwood cuttings of this type, though not strictly required.
Rooting Time
Several weeks to a couple of months.
Bloom & Flower Guide
Quick Details
- Bloom Season: Mainly late winter and spring, often with a lighter second flush later
- Time to First Bloom: Young shrubs generally begin flowering within a few years
- Flower Appearance: Small flowers with long, showy stamens – usually red, sometimes white – packed into a cylindrical bottlebrush spike
- Edibility: Grown as an ornamental; the nectar-rich blooms are loved by birds and bees, but are not a culinary flower
Detailed Blooming Overview
Bottlebrush is named for its cylindrical flower spikes, in which many small flowers with long, brightly coloured stamens are packed around the stem like the bristles of a brush. Flowering mainly in late winter and spring, the nectar-rich blooms are a magnet for nectar-feeding birds and bees.
Flower Characteristics
- Small individual flowers whose long stamens form the showy part.
- Usually red, sometimes white.
- Densely arranged in a cylindrical bottlebrush spike.
Bloom Care & Thinning
- Pruning: Trim lightly just after flowering, cutting behind the spent brushes, to keep growth compact and encourage next season”s bloom.
- Position: Full sun gives the heaviest flowering.
- Wildlife: Leave some blooms for the birds and bees that feed on the nectar.
Pests, Diseases & Troubleshooting
Overview: Callistemon (weeping bottlebrush) is a hardy Australian Myrtaceae shrub that is generally trouble-free, but as a member of the myrtle family it is at risk from myrtle rust and from sap-suckers — scale, mealybugs, aphids and sawfly larvae — while alkaline or waterlogged soils bring on chlorosis and root rot. Good siting in full sun with free-draining soil, plus vigilance for rust, prevents most problems.
Quick Troubleshooting Overview
| Issue / Pest | Main Symptom | Primary Solution |
|---|---|---|
| Myrtle rust | Bright yellow-orange powdery pustules on new leaves, shoots and buds | Remove/bag infected growth, improve airflow; myrtle-rust fungicide |
| Scale & mealybugs | Brown bumps or white fluff on stems; sticky honeydew and sooty mould | Horticultural oil, prune out heavy infestations, encourage predators |
| Aphids | Clusters on soft new tips; distortion and honeydew | Hose off, insecticidal soap or neem; support ladybirds |
| Sawfly / webbing caterpillars | Chewed foliage, larvae feeding in groups | Hand-remove, prune affected shoots; Btk if severe |
| Chlorosis | Yellow leaves with green veins in alkaline or waterlogged soil | Improve drainage, acidify, apply iron/manganese chelate |
| Root rot | Wilting, dieback, dark soft roots in wet soil | Improve drainage, avoid overwatering; phosphonate on Phytophthora |
Common Pests & Management
- Scale insects (Coccidae / Diaspididae):
- Symptoms: Brown, grey or waxy bumps line the stems and leaf undersides; soft scale exude honeydew that blackens with sooty mould, and heavy colonies cause yellowing and dieback of twigs.
- Prevention & Control: Rub off light infestations and prune out badly encrusted stems; spray with horticultural oil to smother scale, repeating in a fortnight, and protect natural predators such as ladybirds and parasitic wasps by avoiding broad-spectrum sprays.
- Mealybugs (Pseudococcus / Planococcus spp.):
- Symptoms: White cottony masses in leaf axils and shoot tips, with honeydew and sooty mould; growth slows and new tips distort under heavy attack.
- Prevention & Control: Dislodge with a water jet or dab with alcohol, then treat with horticultural oil or insecticidal soap, repeating weekly. Ants farm mealybugs for honeydew, so controlling ants helps natural predators do their work.
- Aphids (Aphis / Myzus spp.):
- Symptoms: Soft-bodied green, black or brown clusters on the flush of new growth and flower buds, causing curling and distortion plus sticky honeydew; the main pest noted for bottlebrushes.
- Prevention & Control: Blast them off with water, then use insecticidal soap or neem oil if needed; ladybirds, hoverflies and lacewings usually keep them in check outdoors, so avoid harsh sprays that kill beneficials.
- Sawfly larvae & webbing caterpillars (Pergidae; Lepidoptera):
- Symptoms: Groups of caterpillar-like larvae chew the foliage, sometimes clustering on stems by day, and webbing caterpillars bind leaves and shoots together as they feed, causing ragged, skeletonised growth.
- Prevention & Control: Hand-pick or prune out clusters, which are easy to spot; tolerate light damage on established shrubs. For heavy attacks a Bacillus thuringiensis (Btk) spray targets caterpillars while sparing beneficial insects.
Diseases & Fungal Issues
- Myrtle rust (Austropuccinia psidii):
- Symptoms: Bright yellow to orange powdery pustules erupt on young leaves, shoots, buds and flowers, distorting and killing new growth; a serious disease of the myrtle family that can defoliate and weaken plants.
- Treatment & Management: Inspect new flushes regularly; remove and bag infected material rather than composting it, and disinfect tools. Improve airflow and avoid wetting foliage; apply a fungicide registered for myrtle rust to protect new growth where the disease is active, rotating chemistry to avoid resistance.
- Sooty mould:
- Symptoms: A black, soot-like film coats leaves and stems, growing on the honeydew excreted by scale, mealybugs and aphids; it blocks light rather than infecting the plant directly.
- Treatment & Management: Control the underlying sap-suckers and the mould dries up and flakes away; a gentle wash speeds cosmetic recovery. Managing ants and honeydew producers is the real cure.
- Root rot (Phytophthora / Pythium):
- Symptoms: Wilting, thinning canopy, yellowing and branch dieback despite moist soil, with dark, soft, decayed roots; usually triggered by heavy, poorly drained or overwatered ground.
- Treatment & Management: Plant in free-draining soil, avoid waterlogging, and do not overwater established shrubs. Improve drainage with mounding or grit; a phosphonate treatment can protect valued plants against Phytophthora, but drainage is the fix.
Growing Difficulties & Abiotic Problems
- Chlorosis (iron/manganese deficiency):
- Cause & Symptoms: Yellowing leaves with green veins, worst on new growth, in alkaline or waterlogged soils where the plant cannot take up iron and manganese.
- Correction Strategy: Lower soil pH with elemental sulphur or an acidifying mulch, improve drainage, and apply chelated iron and manganese for a quick correction; mulch and consistent moisture stabilise uptake.
- Waterlogging / root stress:
- Cause & Symptoms: Sudden yellowing, leaf drop and dieback after prolonged wet feet, opening the door to root rot.
- Correction Strategy: Choose a well-drained site, plant on a slight mound in heavy ground, and avoid overwatering; these shrubs prefer full sun and free-draining soil.
- Frost / cold damage:
- Cause & Symptoms: Browned, scorched young growth after unseasonal cold snaps in exposed positions.
- Correction Strategy: Site in a warm, sheltered spot, avoid frost pockets, and delay pruning that would push tender new growth into cold periods.
What Helps – Products & Tools
Most care here is cultural — full sun, free-draining soil and prompt removal of infected growth. Useful products are horticultural oil and insecticidal soap for scale, mealybugs and aphids, a Btk spray for caterpillars/sawfly, a fungicide registered for myrtle rust to protect new flushes, chelated iron/manganese and elemental sulphur for chlorosis, and a phosphonate for Phytophthora root rot.
